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UNT College of Engineering

The UNT College of Engineering strives to educate and train engineers and technologists who have the vision to recognize and solve the problems of society. The college comprises six degree-granting departments of instruction and research.

Degree Information

Description

Article on assessing potential impacts of CO2 and deforestation induced climate change on maize and black bean in Venezuela.

Physical Description

14 p.

Notes

Abstract: We summarize the potential impacts of climate change on the yield of maize (Zea mayz) and black bean (Phaseolus vulgaris L.) at important agricultural sites in Venezuela. The effects of greenhouse-induced global-scale climatic changes and deforestation-induced continental-scale climatic changes were analyzed for both staple crops. The enhanced greenhouse climate scenarios (GH) were derived from atmospheric General Circulation Models for doubled CO2 conditions. GH scenarios of three levels of sensitivity were defined (low, medium and high) from the lower and upper bounds of GCM-derived temperature projections. These GH scenarios assume increased air temperature for both the wet and dry season and increased rainfall and decreased incoming solar radiation for the wet season. Direct effects of increased atmospheric CO2 were included in the bean simulations but not in the maize simulations. The deforestation scenarios (DEF) assume increased air temperature, increased incoming solar radiation and decreased rainfall, as predicted by coupled atmosphere-biosphere models for extensive deforestation of the Amazon basin. The CERES-Maize and BEANGRO crop simulation models, from the Decision Support System for Agrotechnology Transfer (DSSAT), were used for assessing impacts on yield of corn and black bean respectively. The results are only relative because the simulations assumed non-limiting nutrients and no damage from pests or from excess water. The assessments consisted of simulated cultivations of the CENIAP PB-8 maize cultivar grown during the wet season at three sites for two baseline years (in order to cover different rainfall conditions), and the TACARIGUA black bean cultivar grown during the dry season at three sites, for only one baseline climate year. All GH scenarios caused a decrease in yield of corn at all sites: the phenological phases were shortened and the number and weight of kernels were reduced. Low sensitivity GH scenarios produced a slight increase in bean yield, but medium and high GH scenarios decreased bean yield, in spite of the partial compensation by atmospheric CO2 enrichment. Increases of precipitation in GH scenarios had no effects on maize yield, because the sites already have adequate precipitation; however, the crop models used here do not account for potential negative effects of excess water. DEF scenarios produced relatively smaller changes in maize and bean yield. Increased solar radiation increased maize yields for the relatively small increase of air temperatures used in the DEF scenarios. Decrease of bean harvest index for all scenarios indicates that yield is more sensitive to air temperature change than is biomass. The potential reductions in maize and bean yield will most likely be due to increasing temperatures and not to rainfall changes.